The present invention concerns devices with probes for measuring magnetic potentials.
The magnetic potential, .psi., is defined by EQU H=-degree .psi.,
i.e., the magnetic field intensity is the gradient of the magnetic potential field. In principle, only differences of the magnetic potential between two points in a magnetic field can be measured by determining the path integral. ##EQU1## between the points 0 and 1. Here, H is the magnetic field intensity and ds is a path element on any arbitrary line between the points 0 and 1.
When considering the potential difference between a point 1 of a magnetic field and another point 0 located outside the magnetic field, the integral can be described as magnetic potential of the point 1.
It is known that magnetic potentials can be measured with a magnetic fluxmeter and long, thin coils with constant surface density of turns (A. P. Chattock, "Phil. Mag.", 24, 94, 1887). If one end of such a potential coil is moved in a magnetic field from one point to another, while the other end is immobile or is moving in field-free space, an electrical voltage U is generated in it, whose time integral .intg.U dt is measured and indicated by the connected fluxmeter. This [integral] is proportional to the path integral .intg.H.multidot.ds: ##EQU2## in which .mu..sub.0 =0.4.pi..multidot.10.sup.-8 Vsec/A cm, l=length of the measuring coil, n=number of turns, A=area of one turn, t.sub.0 =time at the beginning, t.sub.1 =time at the end of the measurement.
Substantial disadvantages of this prior-art measuring device are, on the one hand, the low sensitivity, when measuring coils with small turn area A are used for better field resolution, and, on the other hand, the drift which is always present in a fluxmeter, which causes an error in measurement especially in the case of prolonged measurements, e.g., during the plotting of the hysteresis curves of magnetic materials. These disadvantages are eliminated by the present invention.